X = int(input())
Y = int(input())
L = int(input())

T = 0
A = abs(X // L)
B = abs(Y // L)

if not X % L == 0:
    A += 1
if not Y % L == 0:
    B += 1
    
if Y < 0:
    T += 2
elif X == 0:
    pass
else:
    T += 1

print(T + A + B)